The invention generally relates to an exhaust gas treatment apparatus for use together with an internal combustion engine in an indoor environment, where the diesel internal combustion is comprised with e.g. a vehicle or other machinery. The invention also relates to a method of controlling a mobile exhaust gas treatment apparatus.
Recent advances in the design and operation of aftertreatment systems for internal combustion engines, typically integrated with a vehicle or other machinery, have radically improved the removal of diesel particulate matter or soot from exhaust gas of the internal combustion engine. Such an aftertreatment system typically includes a diesel particulate filter.
The aftertreatment systems are very robust and durable, but, depending on operation mode, can build up contaminants within the diesel particulate filter, which are primarily carbon particles or soot, that over time affect the system performance. As more particulates accumulate in the filter, the increasing restriction to exhaust flow results in a gradual increase in exhaust back pressure, i.e. the pressure within the exhaust upstream of the filter. If the filter is not properly maintained, the exhaust back pressure may increase to a point which could jeopardize engine component life. There is thus a need to regenerate and desulfate exhaust system components on a regular basis for efficient operation.
Regeneration of diesel particulate filters requires heating the filters to temperatures above 450° C., for a period depending on filter size, type, soot amount and regeneration conditions, for example, for a diesel truck highway operation engine operating normally, for about 10 minutes to over 1 hour.
Under sons conditions, it may be desirable to perform the regeneration under standstill conditions, a so called “parked” or “stationary” regeneration. It offers e.g. the vehicle driver the option, if needed, of performing regeneration outside the normal duty cycle. Under such condition, the mixing of the emitted exhaust may be low, resulting in elevated levels of potentially smelly or hazardous compounds around the vehicle. In addition, care must then be taken in regards to the surrounding of e.g. the vehicle due to the elevated exhaust temperature, typically above 500° C., potentially causing risks of fire within surrounding structures.
Accordingly, it would be desirable to improve the possibility to perform a parked or stationary regeneration of the diesel particulate filter, specifically taking into the potential environmental and temperature related risks mentioned above.
According to an aspect of the invention, the above is at least partly alleviated by an exhaust gas treatment apparatus, comprising an exhaust conduit having a first end adapted to be removably connected to an exhaust pipe of an internal combustion engine, and an adsorption bed comprising an adsorbent material for the adsorption of elements of engine exhaust gases, the adsorption bed being operatively connected to a second end of the exhaust conduit for receiving the engine exhaust gases, wherein the exhaust gas treatment apparatus further comprises a heat adjustment unit arranged upstream of the adsorption bed and downstream of the first end of the exhaust conduit, wherein the heat adjustment unit is configured to adjust a temperature of the engine exhaust gas to be within a temperature range selected based on the adsorbent material.
The present invention, according to an aspect thereof, typically allows for swift handling; of exhaust gases from the internal combustion engine, specifically exhaust gases resulting from a regeneration process of an aftertreatment system comprised with the internal combustion engine, in situations where normally a parked or stationary regeneration generally would be undesirable. Such a situation may for example be when the internal combustion engine is arranged indoors or in relatively close vicinity of human personnel, that is, in situations where potentially smelly or hazardous compounds resulting from the regeneration process would be undesirable to be inhaled by the human personnel and/or where venting is hard to facilitate.
The exhaust gas treatment apparatus according to the invention is arranged external from the internal combustion engine. Specifically, the exhaust gas treatment apparatus is arranged as a separate entity/unit in relation to the vehicle or machinery, advantageously adapted to be connected to different types of vehicles and/or machineries. As such, the exhaust conduit is preferably extendible to allow for connection to an exhaust pipe independent on its placement in relation to the internal combustion engine. Similarly, the first end of the exhaust conduit is preferably adjustable in relation to its circumference, allowing it to be connected to different types of exhaust pipes.
In addition, by means of the invention and the thereto comprised heat adjustment unit, it will also be possible to allow for exhaust gases from different types of internal combustion engines to be processed by the exhaust gas treatment apparatus. As mentioned above, the regeneration process typically requires heating to temperatures above 450° C., a resulting exhaust gas temperature that generally would be unsuitable for direct provision to the adsorption material and/or the adsorption bed. In addition, due to the flexibility of the exhaust gas treatment apparatus for connection to different types of internal combustion engines, it may generally be expected that the exhaust gas temperature during a regeneration process may differ for the different types of internal combustion engines. Accordingly, the controllable heat adjustment unit comprised with the exhaust gas treatment will allow the exhaust gases to be adjusted to best suit the adsorption material and/or the adsorption bed for optimizing the adsorption process.
The exhaust gases generated during the regeneration process typically includes sulphur compounds and particulates. The adsorption bed, by means of the inclusion of the adsorption material, allows for an adsorption process to take place in relation to these exhaust gases. During the adsorption process atoms or molecules comprises with the exhaust gases move from the gaseous phase onto the surface of a solid substrate, in this case the adsorption material arranged within the adsorption bed. Typically, the adsorption material is temperature dependent, and the present invention allows for the adaptation of the exhaust gases to correspond to a desirable temperature range matching the specific (or combination of) adsorption material(s) used. The adsorbent material may for example comprise at least one of CaO, BaO, beta zeolites, and activated carbon.
In a preferred embodiment of the invention the exhaust gas treatment apparatus is mobile. It is thus desirable to combine the component of the exhaust gas treatment apparatus in such a manner that the exhaust gas treatment apparatus may be quickly moved from one internal combustion engine to the next. It would of course be suitable to take into account the handling of possible excess heat generated by the heat adjustment unit, i.e. in an operation of the heat adjustment unit where it is desired to lower the temperature of the exhaust gases. The mobile exhaust gas treatment apparatus may be arranged to be carried between different operational points or may be arranged onto a carriage.
The exhaust gas treatment apparatus preferably also comprises a control unit for controlling the operating the heat adjustment unit. As such the control unit may be configured to adaptively control the heat adjustment unit for optimizing the temperature of the exhaust gases. In an embodiment, the control unit is configured to receive an indication of the temperature of the engine exhaust gas and to operate the heat adjustment unit based on the temperature and the preselected temperature range of the adsorbent material. The temperature indication may for example be provided by means of one or a plurality of temperature sensors comprised with the exhaust gas treatment apparatus, preferably arranged to monitor the engine exhaust gas temperature at or upstream of the heat adjustment unit
In some embodiment of the invention it may be desirable to configure the control unit such that it may receive an indication from the internal combustion engine of an upcoming regeneration. With such information at hand, it could be possible for the control unit to e.g. pre-heat the adsorption material, e.g. for optimal performance already from the initial phase of the regeneration.
In a preferred embodiment of the invention the heat adjustment unit is a heat exchanger. The heat exchanger may be arranged for adjusting the temperature in both an upward and a downward direction, even though the most likely scenario for operating the heat exchanger is for lowering the temperature of the exhaust gases. In an embodiment it may be desirable to connect the heat exchanger to a heating or cooling system arranged in connection to the internal combustion engine, thereby making e.g. good use of excess heat generated by the heat exchanger when lowering the temperature of the exhaust gases. The excess heat may also be used for e.g. heating an environment surrounding the exhaust gas treatment apparatus.
Preferably, the heat adjustment unit additionally comprises a diffusor pipe for allowing mixing of the engine exhaust gases with ambient air. Such an embodiment may in some implementations be sufficient for lowering the temperature of the exhaust gases to be within the desired temperature range for the adsorption material as is indicated above (in such an embodiment seen as forming part of the heat adjustment unit).
In a preferred embodiment of the invention the exhaust gas treatment apparatus further comprises a fan adapted to control an exhaust gas throughput of the adsorption bed. The operation of the fan may possibly be subject to a current temperature of the exhaust gases and/or a current (expected or measured) content of the potentially smelly or hazardous compounds. In addition, the fan ensures that the exhaust gases passed the adsorption bed and refrain from leaking into the surrounding of the exhaust gas treatment apparatus.
In a preferred embodiment the exhaust gas treatment apparatus is arranged for treating exhaust gases via the adsorption bed during a regeneration of an exhaust aftertreatment system of the vehicle or machinery, for example including construction equipment, equipped with the internal combustion engine. The exhaust aftertreatment system may include at least one of a diesel particulate filter, a selective catalytic reduction (SCR) system and a diesel oxidation catalyst (DOC) system.
According to another aspect of the present invention there is provided a method for treating exhaust gases of an internal combustion engine, wherein the method comprises the steps of connecting an exhaust gas treatment apparatus to an exhaust pipe of the internal combustion engine, identifying an engine exhaust gas temperature, adapting the exhaust gas temperature prior to the engine exhaust gases entering an adsorption bed in the exhaust gas treatment apparatus so that the exhaust gas temperature is within a temperature range selected based on an adsorbent material in the adsorption bed, and subjecting the adsorption bed for the exhaust gases for adsorption of elements of the engine exhaust gases. This aspect of the invention provides similar advantages as discussed above in relation to the previous aspect of the invention.
Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims.